Internal documents reveal Shell executives repeatedly raised concerns over the integrity of a major Nigerian pipeline years before widespread pollution incidents triggered lawsuits and international scrutiny.

The case was brought by communities in the Niger Delta who are seeking to hold Shell liable for pollution linked to more than 100 oil leaks between 2011 and 2013.

The correspondence shows Markus Droll, then Shell’s Technical Vice President, warning that the company was “pretty exposed” by its decision to keep the line running.